Asia Defense | Security | East Asia | Oceania

Australia-Japan Frigate Deal Faces 3 Critical Challenges 

Australia’s frigate purchase will likely end up being more complicated than the “zero-change” framing suggests.

A computer-generated image of an Upgraded Mogami-class Frigate (4,800 ton type).

On April 18, Japan and Australia announced the official signing of a milestone contract for Mitsubishi Heavy Industries to construct the first three of Australia’s new general-purpose frigates. 

With the Albanese government committing up to AU$20 billion (US$14.3 billion) over the next decade to its SEA 3000 general-purpose frigate program, the project is set to deepen the Australia-Japan bilateral relationship, long described as a “quasi-alliance,” bringing it closer to the level of a formal military alliance.

However, the nature of the agreement is often misunderstood. Contrary to some perceptions, this is not a government-to-government procurement arrangement akin to the U.S. Foreign Military Sales (FMS) system. Rather, it is a commercial contract between the Australian government and MHI, supported politically by both governments.

At a ceremony in Melbourne, Japan’s Defense Minister Koizumi Shinjiro and Australia’s Deputy Prime Minister and Defense Minister Richard Marles signed a Memorandum of Cooperation (MoC), known as the “Mogami Memorandum,” reaffirming their intent to deepen defense industrial cooperation. Yet one industry source confirmed to The Diplomat that the contract work had been completed and signed off in late March, suggesting the April event served more as political signaling than as a formal conclusion. The choice of Melbourne – Marles’ electoral district – as the backdrop further underscores the political dimension of the announcement.

On April 18, MHI formally announced the company had concluded a contract with the Australian government for the construction of three upgraded Mogami-class frigates for Australia’s General Purpose Frigate (GPF) program.

The contract – covering the first three vessels of a planned 11-ship fleet – represents Japan’s largest postwar defense export case and highlights deepening strategic alignment between the two U.S. allies in the Indo-Pacific.

As the program moves from political commitment to implementation, however, three critical challenges are coming into sharper focus.

The first is the sustainability of Australia’s much-publicized “zero-change” approach. Canberra has repeatedly emphasized that adopting the Japanese design with minimal modification would be key to controlling costs and accelerating delivery. Early discussions even suggested that changes would be limited to minor adjustments – such as switching onboard language displays from Japanese to English – implying that the platform could be transferred largely “as is.” 

In practice, the Australian variant will differ significantly from the Japan Maritime Self-Defense Force’s upgraded Mogami-class design. It is expected to integrate the Evolved Sea Sparrow Missile (ESSM) Block 2 for air defense, the Naval Strike Missile (NSM) for anti-ship warfare, and the Mk 54 lightweight torpedo – none of which are standard systems in the Japanese configuration. By contrast, the upgraded Mogami class to be operated by the MSDF will employ domestically developed systems, including the Type 23 ship-to-air missile (A-SAM), the upgraded Type 12 surface-to-ship missile (ship-launched variant), and the Type 12 torpedo.

These are not simple substitutions. Integrating different systems requires modifications to the........

© The Diplomat